1. Field of the Invention
The present invention relates to a cleaning sheet for removing foreign matter adhering on the tip of a probe needle of a probe card and its production method and to a transporting member having such a cleaning sheet as well as to a cleaning method for removing foreign matter from the tip of a probe needle by using the cleaning sheet or transporting member.
2. Description of a Related Art
Probe cards are used for conduction tests of chips formed on a semiconductor wafer. The conduction test is performed by contacting a probe needle of a probe card on an electrode pad formed on the surface of a chip and measuring a contact resistance of the probe needle, according to which it is judged whether the chip is good or defective. The test of wafers is performed as follows. When a probe needle is contacted on an electrode pad formed of, for example, aluminum a constant pressure is applied so that the tip of the probe needle scrapes natural oxide film consisting of aluminum oxide or the like formed on the surface of the electrode pad, ensuring establishment of electrical connection between the probe needle and the electrode pad. Adherence of the aluminum oxide or the like scraped out by the probe needle and having insulating properties on the tip of the probe needle will result in variation of the contact resistance upon contacting the probe needle on the electrode pad, which may cause some trouble in subsequent conduction tests. Therefore, the foreign matter adhering on the tip of the probe needle must be removed periodically.
Methods of removing foreign matter adhering on the tip of a probe needle are disclosed in, for example, Japanese Patent Application Laid-open Nos. 7-244074, 10-300777, and 10-339766, in which the tip of the probe needle is contacted on a layer made of a resin having dispersed therein an abrasive material such as diamond powder, alumina, silicon carbide, or glass or a layer on which such an abrasive material is fixed with an adhesive to remove the foreign matter. Further, Japanese Patent Application Laid-open No. 10-19928 discloses a method of removing foreign matter by using a cleaning sheet having a pressure-sensitive adhesive force (as measured according to Japanese Industrial Standards JIS Z 0237) of 100 g/25 mm to 250 g/25 mm. Japanese Patent Application Laid-open No. 11-133116 discloses a method of removing foreign matter by using a cleaning sheet made of at least one of metal fiber, carbon fiber, and ceramic fiber.
However, in the method of removing foreign matter by contacting the tip of a probe needle on the cleaning layer containing an abrasive material such as diamond powder, the probe needle itself is worn off by the abrasive material upon cleaning, resulting in a shortened service life of the probe card. In the case where the foreign matter once removed from the tip of the probe needle by cleaning adheres again to the foot of the needle, the foreign matter may fall on a wafer to contaminate the wafer upon a subsequent conduction test. The method of removing foreign matter by using a cleaning sheet having a pressure-sensitive adhesive layer thereon causes no problem of wearing off of the probe needle or re-adhering of the foreign matter on the probe needle. However, the method still has the problem that the foreign matter strongly fixed to the probe needle cannot be removed or a part of the pressure-sensitive layer is transferred onto the probe needle, thus causing the problem of so-called adhesive deposit. With the method of removing foreign matter by using a cleaning sheet made of at least one of material filer, carbon fiber, and ceramic fiber, the effect of reducing the wearing off of the probe needle or re-adhering of foreign matter is confirmed but perfect removal of the foreign matter is not achieved.